They're using Rust, which is a great language for this sort if hardware: It can run on hardware itself, and can make responsive, PC applications to interface with it. Perfect excuse not to use a web UI, but this article is demoing one anyway.

EGUI is ideal for this sort of thing. Can make hardware interfaces (eg using USB as a serial port or HID device) into a fast GUI program. Add WGPU if you need anything 3d rendered.